1. Community Ecology Feral cat populations can be damaging to ecosystems.
Why?
Photo Credit:

2. 47.1 Concept of the Community
Community = assemblage of populations interacting with one another
Example: squirrel, moose, bear, fox, wolf, pine tree, termites, bacteria....etc
Videos:  Monkey vs Tiger  | Cobra vs Mongoose | Sea Lion vs Whale

3. 47.2 Structure of the Community
Habitat = particular place an organism lives
Ecological Niche: the role it plays in the community (includes food sources, reproduction, placement)
Fundamental Niche - all the conditions that an organism can survive
Realized niche - where it actually exists in nature

4. Niche – each member of this community gathers food in a unique way

5. Realized vs Fundamental NicheInterspecific Competition: competition between different species
Competitive Exclusion Principle - no two species can occupy the same niche Resource Partitioning - species with niche overlap, share/partition resources (see balanus)

6. Lab: Population Biology
Graph illustrates what happens when you grow two different species of protists separately and in the same container (where competition can occur).
Summarize the results.
Lab:   Population Biology

7. Generalist - eat different things, live in a variety of spaces (raccoon) Specialist - very specific needs (panda)

8. Another example of competitive exclusion and resource partitioning

9. Predator Prey Interactions - communities follow this pattern
Predator Prey Interactions - communities follow this pattern. Prey species increase in number, followed by predator species. Then Prey species decline, followed by predator species decline. The cycle repeats.

11. Prey Defenses
Camouflage (cryptic coloration) - blending in
Mimicry - one species resembles another as a defense (milk snake)

12. Other Defenses
Herding Behavior (zebra) Startle Behavior (blowfish) Anatomical defense (porcupine) Chemical defense (skunk)

13. Figure 47.12b

14. Mimicry

15. Symbiotic Relationships
Symbiosis - intimate relationship between two or more species
Parasitism - one individual is harmed, the other benefits (ticks & deer)
Mutualism - both benefit (flowers & honeybees)
Commensalism - one benefits, other is neither harmed or benefited (clown fish & sea anemone)

16. Commensalism

17. Mutualism

18. Figure 47.17

19. 47.3 Community Development
Ecological Succession - involves a series of species replacements
Primary Succession - occurs where there is no soil formation (volcanic island)
Secondary Succession - occurs after an area is disturbed (prairie fire)
Pioneer Species - first species to inhabit an area
Climax Community - when the species replacement slows and the ecosystem stabilizes

20. Worksheet: Succession

21. 47.4 Community Biodiversity
Intermediate Disturbance Hypothesis - moderate disturbances in an ecosystem are necessary to maintain biodiversity
Keystone Species - needed to maintain biodiversity (often top predators)
Ex: Kelp, Sea otters, Sea urchins, Abalone - what happens when you remove the otters

22. Case Studies in Keystone Species
 KEYSTONE SPECIES:  SEA OTTER
Sea otters eat sea urchins Sea urchins eat kelp What happens when you remove the otters?
Case Studies in Keystone Species

23. Carnivorous starfish Pisaster ochracceus, played a key role in maintaining the balance of all other species in the community. Paine observed that if Pisaster ochracceus was removed from the community, the populations of two mussel species within the community grew unchecked. Without a predator to control their numbers, the mussels soon took over the community and crowded out other species, greatly reduced the community's diversity.

24. Invasive and Parasitic Species 11
The interesting cases of:
1.  Cuckoo and Cowbirds 2.  Kudzu
3.  Asian Carp
4.  Snakehead catfish
5.  Zebra mussels
*Each of these have a negative impact on the environment.

25. Parasitic Bird? Cowbirds (and cuckoos) lay their eggs in other bird’s nests.

26. Invasive Species (exotics)
Kudzu

27. Snakehead Catfish